


pub fn strprint(){
  let mut s = String::from("hello");
  s.push_str("world");
  println!("{}",s);
  println!("s is len :{}",s.len());
}


pub fn first_word(s: &String) -> &Str{
let bytes = s.as_byte();
 for(i ,&item) in bytes.iter().enumerate(){
     if item ==b' '{
         return &s[0..i];
     }

    return &s[..];
 }


}
